1. Field of the Invention
The invention pertains to translation from one signal environment to another and more particularly to an interface architecture for an electronic communication/data processing system providing translation between an emitter coupled logic (ECL) signal environment and a transistor-transistor logic (TTL) or complementary metal-oxide-semiconductor (CMOS) signal environment.
2. Description of Prior Art
As the design of integrated circuits has advanced and as their use has spread into virtually all sectors of technology, distinct families of logic circuits have evolved such as ECL, TTL, CMOS, BiCMOS and the like. Depending on whether an engineer is designing a customized chip, a multi-chip array or an entire system, design constraints such as propagation delay, power dissipation, noise margin, fan-out, size packaging, required power supply(s) and the like will determine which family or families of circuits should be used. Because each chip or system is virtually certain to require interfacing with other chips or systems having different design constraints and applications, communication between different signal environments and system architectures has been a persistent and growing problem. Fundamental to communication between signal environments is the consideration and definition of the logic levels of the input signals which operate the control input terminals or pins of the individual integrated circuits. Different families of logic circuits have different logic levels of input/output signals.
In large complex systems such as processors, for example, translation from one logic level to another generally occurs at a bus interface where most data is transmitted. The control of the devices performing the translation between signal environments or logic levels becomes in this instance a primary consideration. Conventional approaches to translation assume that the logic levels of the input signals which operate the control input pins originate from a single signal environment or logic family. With modern systems, this assumption is not always true. Thus, a need has arisen for a single effective translator between signal environments that can operate with input control signals having different logic levels originating from different signal environments.